A physical quantity sensor disclosed in the related art includes an acceleration sensor provided with a sensing portion outputting a sensor signal corresponding to acceleration and an angular velocity sensor provided with a sensing portion outputting a sensor signal corresponding to an angular velocity, both of which are housed in a housing space of a common case (see, for example, Patent Literature 1).
The acceleration sensor is desirably at rest while no acceleration is applied. Hence, it is preferable that the acceleration sensor detects acceleration under an atmospheric pressure at which air damping (flow resistance of gas) is high. On the contrary, the angular velocity sensor has a vibrating element and detects an angular velocity while the vibrating element is vibrating. It is therefore preferable that the angular velocity sensor detects an angular velocity under a vacuum pressure at which air damping is low for the vibrating element to readily vibrate.
In a case where the acceleration sensor and the angular velocity sensor are housed in the housing space of the common case, for example, a pressure in the housing space is set to a vacuum pressure and the angular velocity sensor is directly installed in the housing space. Meanwhile, the acceleration sensor is installed in the housing space in a state of a package structure in which a sensing portion is hermetically sealed in an airtight chamber set to an atmospheric pressure.